Conflicting data exist in the limited number of published studies evaluating human lymphocyte responsiveness to pollen allergens. Studies by the investigator have revealed vigorous DNA synthetic responsiveness to purified ragweed pollen antigens by lymphocytes from normal nonatopic, newborn and agammaglobulinemic subjects, as well as from both treated and untreated atopic subjects, suggesting that these pollen antigens are either ubiquitous and lead to cell-mediated responses in all subjects with intact cell-mediated immunity or that they may have mitogenic properties in addition to their known antigenic properties. The proposed research will evaluate DNA synthetic and immuno-globulin biosynthetic responses of lymphocytes and lymphocyte subpopulations from atopic and nonatopic subjects to both crude and purified pollen antigens of several types in order to determine 1) whether other pollen antigens have broad stimulatory properties similar to those of ragweed antigens, 2) whether responses of either type differ for atopic and nonatopic subjects, 3) whether responses to pollen antigens by lymphocyte subpopulations differ for atopic and normal subjects, 4) whether soluble factors released from pollen antigen-stimulated T lymphocytes capable of stimulating B cells differ in quality or quantity for atopic and nonatopic subjects, 5) whether changes occur in either of the two types of responses in atopic subjects undergoing pollen extract immunotherapy, and 6) whether a deficiency exists in atopic subjects of a subpopulation of T cells important in regulating IgE antibody synthesis.